This invention relates to a dynamoelectric machine having ventilating openings with foreign matter restrictive construction to selectively control the entrance of foreign matter and particularly animals.
Dynamoelectric machines including alternators and motors are conventionally constructed with a tubular main frame and end bells or brackets releasably secured to the opposite ends of the main frame. An annular stator unit is secured within the tubular main frame. A rotor is mounted within the stator unit, with shaft means projecting from the opposite ends and rotatably mounted in suitable bearings in the end brackets.
A fan unit is often incorporated into the rotor structure within one end bracket for generating of air flow through the motor. The end brackets are provided with appropriate openings to permit the air flow through the motor. The openings in the end bracket are advantageously formed with an integral grill work to maintain the strength of the end bracket while allowing appropriate volumes of air flow through the dynamoelectric machine.
In many applications, relatively significant openings are formed within the end brackets. In certain applications, special end bracket constructions are required to further restrict the size of the openings to minimize entry of small animals, including mice, snakes and like sized animals Motors for such applications may include a standard motor within which a special screen member is welded to the interior surface of the end bracket in overlying relationship to the air flow openings. Generally, a screen member is shaped to conform to the interior surface at the air openings and welded within the end bracket to overly the air openings. The motor end brackets can of course be specially constructed with appropriately sized openings. U.S. Pat. No. 5,081,384, which issued on Jan. 14, 1992, particularly discloses a ventilated motor having an end bracket within which a baffle and air deflector unit is integrally cast into the end bracket. The deflector openings are said to be of a sufficient size to prevent entrance of small animals, snakes and the like.
U.S. Pat. No. 2,500,971 which issued Mar. 21, 1950, illustrates a motor having large ventilating openings which are covered by screen units bolts over the openings by special bolts and bolt openings formed in the side wall of the frame which is extended downwardly to form a supporting base. This patent thus teaches and suggests a special motor structure providing special external mounting components for covering of the ventilating opening with a special separate screen through the use of totally separate mounting components.
In certain motors, the air flow openings are formed in the end face and the adjacent sidewalls as a plurality of closely spaced edge openings. In other motors, a single relatively large grilled opening is formed in the sidewall of one end frame. Generally, each manufacturer makes a line of standard motors with standardized ventilating openings.
Such prior art devices are well known in the art and have provided a satisfactory enclosure for the effective exclusion of small animals and the like. There is a need for a relatively simple and inexpensive system for modifying of a standard motor to the requirements of special applications which require animal-proof type enclosure and particularly such a motor system which is conveniently adapted to field application. Under such a system, distributors, sellers and users of motors may stock standard air-cooled motors and provide for special animal exclusion construction by modification of such motors.
There is a need for a simple, reliable and effective method for converting of a standard motor to a rodent guarded motor without requiring shop service and reworking.